MPs fight for the slimmest majority in the Commons

When MPs start their careers in politics they gain a House of Commons office; tens of thousands of constituents; and — it seems — a great deal of weight.

The “Parliamentary stone” is being cited by politicians as the most unusual side-effect of their professions. That, they say, is the scale of bloating that tends to take place within the first five years.

Perhaps it is the working lunches; the subsidised food and alcohol; the scones pushed on to you at village fetes; or the hours spent seated on green benches.

Whatever the reason the trend has triggered another Westminster rivalry — alongside that between Labour and the Tories and David Cameron and Nick Clegg. This is a battle of Slimming World vs WeightWatchers.